• 대한치과보철학회지
• /
• 제59권3호
• /
• pp.319-332
• /
• 2021

심미적인 도재 재료와 레진 시멘트의 비약적인 발전으로 임상에서 금속도재관에서 전부도재관으로의 전환이 활발히 이루어지고 있으며, 도재 수복물 제작 시 그에 적합한 형태와 기술을 이용하여야 그 장점을 최대화할 수 있다. 최근 법랑질을 최대한 보존하고 접착 효율을 높이는 최소 침습적 치아 삭제법을 적용하여 치은 연상 변연을 가진 심미적인 도재 부분피 개관 수복방법이 소개되었는데, 이를 통해 치질 삭제의 최소화, 시멘트 제거의 용이성 등 여러 장점들을 얻을 수 있다고 보고된다. 또한 이 제작법은 치은 압배사의 삽입이 불필요하여 치은 압배사 삽입에 소요되는 시간을 절약할 수 있으며 환자의 불편감도 감소시킬 수 있다. 더 나아가 치은 열구액이나 혈액의 개입 없이 명확하게 변연을 채득할 수 있어 더 정확한 수복물 제작이 가능하다고 보고된다. 본 증례에서는 각각 해당 치아 부위에 부분적인 결함이 있는 환자에서 통상적인 전부피개관이 아닌 접착치의학 개념에 따른 최소 침습적 치아 삭제법을 적용한 치은 연상 변연 도재 부분피개관으로 다양한 제작 방법을 활용하여 수복함으로써 불필요한 치아 삭제를 방지하고 잔존 치질을 최대한 보존할 수 있었다. 치료 후 환자와 술자 모두 심미적, 기능적으로 만족할 만한 결과를 얻었기에 이를 보고하는 바이다.

• Restorative Dentistry and Endodontics
• /
• 제45권4호
• /
• pp.49.1-49.11
• /
• 2020

Objectives: The aim of this study was to perform a clinical and radiographic analysis of endodontically treated teeth (ETT) restored with cast metal posts (CMPs) or prefabricated glass fiber posts (GFPs) and crowns. Materials and Methods: Fifty ETT were restored with 25 CMPs and 25 GFPs at a private dental clinic between 2001 and 2016. The restorations consisted of 12 all-ceramic crowns, 31 metal-ceramic crowns, and 7 composite resin crowns. Demographic data, type of teeth, type of post-and-core system, time of placement, crown restorations, the number of proximal contacts, the type of antagonist, and reports of any complications after post-and-core placement were recorded for each patient. Assessments were performed at baseline (radiographic) and follow-up (radiographic and clinical). Data were analyzed by the McNemar test, the Pearson χ² test, and Kaplan-Meier survival curves (α = 0.05). The mean follow-up was 67.6 months. Results: No significant difference was observed for any of the radiographic parameters when the baseline and final radiographs were compared. In the clinical evaluation, anatomical form (p = 0.009) and occlusion (p = 0.001) showed significant differences according to the type of crown restoration; specifically, metal-ceramic and all-ceramic crowns outperformed composite resin crowns. Conclusions: CMPs and GFPs showed favorable results for restoring ETT after 6 years of follow-up. All-ceramic and metal-ceramic crowns showed higher survival rates and better clinical outcomes.

• 대한치과기공학회지
• /
• 제33권1호
• /
• pp.15-23
• /
• 2011

Purpose: Thy yttria tetragonal zirconia polycrystalline(Y-TZP) is a good structural ceramic for dental restoration. But it have a problem that delamination of veneering ceramic from the Y-TZP core materials. The problem generally occur at the interface, thus this study was conducted to evaluate the interface of Y-TZP using scanning electron microscopy(SEM). Methods: To investigate this aspect, high-resolution SEM observations were made of polished and etched (HF content gel) cross-sections of the interface area. Dry and moist veneering porcelain powders were built up on the zirconia base. Results: The extent of this surface faceting is dependent upon the moisture content of the porcelain powder and the firing temperature. More moisture and higher final heating temperature accelerates the observed faceting of the Y-TZP grains at the interface to the veneering ceramic. Conclusion: These changes of the Y-TZP grains indicate that destabilization of the tetragonal phase of zirconia occurs at the interface during veneering with ceramic. It may result in a reduction of the stability of the zirconia and interface.

• 대한치과보철학회지
• /
• 제42권5호
• /
• pp.514-523
• /
• 2004

Statement of problem: All-ceramic restorations have been advocated for superior esthetics. Various post and core systems have been used to improve the strength of damaged teeth, but it is unclear whether they affect the final shade of finished all-ceramic restorations. Purpose: The influence of different types of post and core systems on light transmission through all-ceramic crowns was assessed by spectrophotometric analysis. Also the masking effect of different thickness of ceramic ingot was evaluated. Material and Methods : Forty-five sample disks (15mm in diameter) at several thickness(1.0, 1.5, 2.0mm) and value(shade 100, 200, 300) were made in heat pressed ceramic(IPS-Empress). Background specimens simulating gold-alloy cast posts(Type III casting gold alloy), metal posts(Ni-Cr casting alloy) and ceramic posts(CosmoPost) were fabrica-ted. Resin composite(Z250, A3 shade) was used as a tooth substrate reference. For each combination, the change in color was measured with a spectrophotometer. Readings were performed for 2 conditions (1) ability of ceramic to mask the core in relation to its thickness(1.0, 1.5, or 2.0mm) ; (2) influence of post and core types on the final color of the ceramic. Data were recorded according to the CIE $L^*a^*b^*$ systems and color difference($\Delta$E) was calculated. Results: 100 shade ingot: when ceramic thickness was 1.0mm, $\Delta$E value for ceramic post larger than 1 but $\Delta$E value for metal and gold post was larger than 2. For ceramic thickness of 1.5mm, only $\Delta$E value for metal was larger than 2, and the other samples' $\Delta$E value was smaller than 2. For ceramic thickness of 2.0mm, $\Delta$E values for all specimens was smaller than 2. 200 shade ingot: when ceramic thickness was 1.0mm, $\Delta$E value for ceramic post was smaller than 1 but $\Delta$E value for metal and gold post was larger than 2. For ceramic thickness of 1.5 mm, only the $\Delta$E value for metal was larger than 2, and the other samples' $\Delta$E value was smaller than 2. For ceramic thickness of 2.0mm, $\Delta$E values for all specimens was smaller than 1. 300 shade ingot: when ceramic thickness was 1.0mm, only $\Delta$E value for metal was larger than 2 and the other samples' $\Delta$E value was smaller than 2. For ceramic thickness of 1.5mm, $\Delta$E values for all specimens was smaller than 1. For ceramic thickness of 2.0mm, $\Delta$E values for all specimens was smaller than 1. Conclusion: The final esthetic result of the IPS-Empress glass-ceramic restoration was not affected by the presence of different core materials when the thickness was more than 2.0 mm. When ceramic thickness decreases to 1.5mm, it is advised to take the substrate aspects into consideration. If the ceramic thickness is less than 1.0mm, using the tooth color matched substrate is strongly recommended.

• 대한치과보철학회지
• /
• 제37권5호
• /
• pp.658-671
• /
• 1999

The major influencing factors on the strength of all-ceramic crowns are types of dental ceramics, fabrication techniques, methods of abutment preparation and cementation modes of all-ceramic restorations. Zinc phosphate cement and glass-ionomer cement were used as an early lot-ing media for all-ceramic crowns. Recently many studies have reported that resin cements have more advantages in increasing the fracture strength of restorations comparing with zincphosphate cement and glass-ionomer cement. The purpose of this study is to investigate the effect of etching, silane treatment, sandblasting and dentin bonding agents on fracture strengths of dental ceramics. 40 flat dentin specimens and 40 ceramic discs of 1.5mm thickness and 8mm diameter were fabricated, and divided into 4 groups according to surface treatments. Surface treatments before cementation were as follows Group I : (ceramic) : HF etching - silane treatment - application of bonding resin (dentin) : application of dentin bonding agent Group II : (ceramic) : sandblasting - application of bonding resin (dentin) : application of dentin bonding agent Group III : (ceramic) : application of bonding resin (dentin) : application of dentin bonding agent Group IV : (ceramic) : HF etching - silane treatment - application of bonding resin (dentin) : no dentin bonding procedure Dentin specimens and ceramic discs were cemented with dual cure resin cement, and went through thermocycling. Compressive stress es were loaded on the centers of ceramic discs with Instron test-ing machine, and fracture strengths resistance for catastrophic fracture were measured The results were as follows. 1. The group I showed the highest fracture resistance. The next was group II And group III, IV followed. 2. There was a significant difference in the mean value of fracture strengths between group I and group III (p<0.05), but no significant differences between group I and group II, and group II and group III (p>0.05). 3. There was a significant difference in the mean value of fracture strengths between group I and group IV (p<0.05).

• The Journal of Advanced Prosthodontics
• /
• 제10권1호
• /
• pp.18-24
• /
• 2018

PURPOSE. In literature, many studies compare survival rates of different types of FPDs. Most of them compared restorations, which originated from one university, but from different clinicians. Data about restoration survival rates by only one experienced dentist are very rare. The aim of this study was to evaluate the survival rate of all-ceramic FPDs without the blurring effects of different clinicians. MATERIALS AND METHODS. 153 veneered-zirconia FPDs were observed for follow-up. 22 patients received 131 single crowns and 22 bridges. Because of the different bridge lengths, one unit was defined as a restored or replaced tooth. In total, 201 units were included. Only the restorations performed by the same clinician and produced in the same dental laboratory from 2011 to 2016 were included. Considered factors were defined as "type of unit", "type of abutment", "intraoral region", and "vitality". Modified UHPHS criteria were used for evaluation. Statistical analysis was performed using cox-regression. RESULTS. 189 units (94.0%) showed no kind of failure. 5 chippings (2.4%) could be corrected by intraoral polishing. 4 units (1.9%) exhibited spontaneous decementation. These polishable and recementable restorations are still in clinical use. Chippings or decementations, which lead to total failure, did not occur. One unit was completely fractured (0.5 %). Biological failures (caries, periodontitis or periimplantitis) did not occur. The statistical analysis of the factors did not reveal any significant differences. CONCLUSION. Modern all-ceramic FPDs seem to be an appropriate therapy not only for single restorations but for complex occlusal rehabilitations.

• 대한심미치과학회지
• /
• 제19권1호
• /
• pp.38-41
• /
• 2010

• 보존과학회지
• /
• 제36권4호
• /
• pp.275-283
• /
• 2020

Iron oxides are the essential coloring oxides in traditional ceramic glazes. However, when Fe is involved in the coloration in the form of ions or colloids in glazes with low Fe content, it is difficult to identify the iron oxide phases. Generally, in many these glazes, Ca-rich minerals are observed by X-ray diffraction (XRD) or microscopic images, owing to their devitrification by the high Ca content. This study attempts to elucidate the correlation between the crystalline structure and coloration in the glazes while mainly focusing on neoformed Ca-rich minerals and Fe content. An experimental firing was carried out to produce tree ash glazes, with pine tree ash and Buyeo feldspar. In the case of oxidation glazes, the scanning electron microscopy (SEM) images and XRD patterns did not exhibit any Ca-rich crystals, and all the visible light reflectance spectra lines exhibited a similar shape. In contrast, the reduction glazes divided into blue glazes and other colored glazes according to the shapes of their reflectance spectra. It was confirmed that the influence of Ca-rich minerals on the glaze color was more pronounced than the blue color of the reduction glazes when the Ca and feldspar contents were sufficiently high and low, respectively, to form wollastonite. As the Ca content increased and the elemental composition of the reduction glazes changed, the neoformation of the Ca-rich minerals, such as wollastonite, anorthite, diopside, and akermanite was sequentially observed.

• 대한치과기공학회지
• /
• 제34권2호
• /
• pp.95-103
• /
• 2012

Purpose: Fracture strength of all-ceramic 3-unit fixed partial dentures manufactured by CAD/CAM and copy-milling systems were evaluated. Methods: Zirconia cores were made by milling the pre-sintered zirconia block by CAD/CAM or copy milling method followed by subsequent sintering. By building-up the corresponding porcelains on the core, all-ceramic bridges were fabricated, and those were evaluated in comparison with PFM fixed partial denture. Results: During the flexural test of the 3-unit PFM bridge, the porcelain started to chip or break at 507.28(${\pm}62.82$)kgf and the metal framework did not break until the maximum load level of 800kgf which was set in the testing instrument of this study. However, among all-ceramic restoration test groups, Everest(EV) group showed a peeling off or breakage of the porcelain from 365.64(${\pm}64.96$)kgf and the core was broken at 491.77(${\pm}55.62$)kgf. Those values of Zirkonzahn(ZR) were 431.03(${\pm}58.47$)kgf and 602.74(${\pm}48.44$)kgf, respectively. The break strength of the porcelain of PFM(PM) group was significantly higher than that of EV (p<0.05) group and there was no significant difference when comparing to that of ZR (p>0.05). ZR group showed higher break strength than that of EV group however there was no significant difference (p>0.05). The break strength of cores were in the increasing order of EV < ZR < PM (p<0.05). Conclusion: We could find that even though the PM group fractured at much higher value than all-ceramic cores, the breakage values of the porcelain of PM group with crack formation or delamination, which will be regarded as clinical failure, was significantly higher than that of EV group and not significantly higher than that of ZR group at p-values of 0.05. The break strength of ZR group was higher than that of EV group at an insignificant level(p>0.05).

• The Journal of Advanced Prosthodontics
• /
• 제12권6호
• /
• pp.344-350
• /
• 2020

PURPOSE. Recently introduced hybrid and reinforced glass ceramic computer-aided design/computer-aided manufacturing (CAD/CAM) materials have been used for full-coverage restorations. However; the effect of adjustment and type of materials on internal and marginal adaptation are unknown. This study aimed to evaluate and compare the marginal and internal adaptations of crowns made of three different CAD/CAM materials before and after adjustment. MATERIALS AND METHODS. One acrylic resin maxillary first molar was prepared and served as the master die. Thirty-six restorations were fabricated using CAD/CAM system (CEREC Omnicam, MCXL) with three materials including lithium disilicate (IPS e.max CAD), zirconia-reinforced lithium silicate (Suprinity), and hybrid ceramic (Enamic). Internal and marginal adaptations were evaluated with the reference point matching technique before and after adjustment. The data were analyzed using mixed ANOVA considering α=.05 as the significance level. RESULTS. The effect of adjustment and its interaction with the restoration material were significant for marginal, absolute marginal, and occlusal discrepancies (P<.05). Before adjustment, Suprinity had lower marginal discrepancies than IPS e.max CAD (P=.18) and Enamic (P=.021); though no significant differences existed after adjustment. CONCLUSION. Within the limitations of this study, crowns fabricated from IPS e.max CAD and Suprinity resulted in slightly better adaptation compared with Enamic crowns before adjustment. However, marginal, axial, and occlusal discrepancies were similar among all materials after the adjustment.